linux-kernel - [PATCH 5.4 052/214] media: uvcvideo: Fix dereference of out-of-bound list iterator

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Date:   Tue,  3 Nov 2020 21:35:00 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Daniel W. S. Almeida" <dwlsalmeida@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 052/214] media: uvcvideo: Fix dereference of out-of-bound list iterator

From: Daniel W. S. Almeida <dwlsalmeida@...il.com>

[ Upstream commit f875bcc375c738bf2f599ff2e1c5b918dbd07c45 ]

Fixes the following coccinelle report:

drivers/media/usb/uvc/uvc_ctrl.c:1860:5-11:
ERROR: invalid reference to the index variable of the iterator on line 1854

by adding a boolean variable to check if the loop has found the

Found using - Coccinelle (http://coccinelle.lip6.fr)

[Replace cursor variable with bool found]

Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@...il.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index a30a8a731eda8..c13ed95cb06fe 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1848,30 +1848,35 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
 {
 	struct uvc_entity *entity;
 	struct uvc_control *ctrl;
-	unsigned int i, found = 0;
+	unsigned int i;
+	bool found;
 	u32 reqflags;
 	u16 size;
 	u8 *data = NULL;
 	int ret;
 
 	/* Find the extension unit. */
+	found = false;
 	list_for_each_entry(entity, &chain->entities, chain) {
 		if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT &&
-		    entity->id == xqry->unit)
+		    entity->id == xqry->unit) {
+			found = true;
 			break;
+		}
 	}
 
-	if (entity->id != xqry->unit) {
+	if (!found) {
 		uvc_trace(UVC_TRACE_CONTROL, "Extension unit %u not found.\n",
 			xqry->unit);
 		return -ENOENT;
 	}
 
 	/* Find the control and perform delayed initialization if needed. */
+	found = false;
 	for (i = 0; i < entity->ncontrols; ++i) {
 		ctrl = &entity->controls[i];
 		if (ctrl->index == xqry->selector - 1) {
-			found = 1;
+			found = true;
 			break;
 		}
 	}
-- 
2.27.0